3.8 Tundra and Polar Regions

258 Credit: Andrew Magor/UNEP/Topfoto 259 3.8 Tundra and Polar Regions f all the terrestrial biomes, tun- permanently frozen subsoil called per- Circle in the Southern Hemisphere (EEA dra is the coldest. Tundra comes mafrost. Because the topsoil is so shallow n.d.). Although similar in many ways, the Ofrom the Finnish word tunturia, and underlaid by permafrost, it becomes two polar regions differ in that the Arctic which means treeless plain (Pullen 1996). quickly saturated with water. Lakes, ponds, is a frozen ocean surrounded by land, There are two distinct types of tundra: the and bogs dot the surface of the Arctic tun- whereas the Antarctic is a frozen continent vast Arctic tundra and high-altitude alpine dra throughout the brief summer months, surrounded by ocean. tundra on mountains. providing moisture for plants and Most of the world’s fresh water is Arctic tundra is located in the Northern nesting and feeding habitats for huge locked up in polar ice caps. Large glaciers Hemisphere on lands encircling the North numbers of waterfowl and other and ice sheets cover Arctic islands and Pole and extending south to the conifer- animals (Pullen 1996). Greenland in the north and the conti- ous boreal forests of the taiga and covering Alpine tundra is found on mountains nent of Antarctica in the south. Where ice approximately 5.6 million km2 (2 million throughout the world, at high altitudes— sheets and glaciers meet the ocean, huge square miles) Wookey 2002). Arctic tundra above the tree line—where conditions are chunks of ice continually break off, in a is characterized by cold, desert-like condi- too cold and too dry for trees to grow. The process known as calving, to give birth to tions. Although somewhat variable from growing season in alpine tundra is approxi- icebergs. Icebergs are found in both Arctic place to place, precipitation on the Arctic mately 180 days. Nighttime temperatures and Antarctic polar oceans. In the north, tundra, including melted snow, is roughly are usually below freezing. Unlike soils in most icebergs are calved from ice sheets 15 to 25 cm (6 to 10 inches) annually. The the Arctic tundra, soils in alpine tundra are along the western coast of Greenland. In average winter temperature is -34° C (-30° usually well-drained (Pullen 1996). Alpine the south, the vast ice sheets and glaciers F); the average summer temperature is 3 to tundra is also characterized by relatively that cover Antarctica give rise to icebergs 12° C (37 to 54° F). Winters are long and high biodiversity. in polar seas. summers brief, with the growing season The Earth’s polar regions are high-lati- The Earth’s tundra and polar regions only 50 to 60 days long. During summer, tude zones above the Arctic Circle in the are unique and vital parts of the global only the top few centimeters of the soil Northern Hemisphere and the Antarctic environment. They are the world’s least thaw. Beneath the surface is a layer of Credit: Brendan C. Fri/UNEP/Topfoto 260 Arctic Region �� 10ºC (50ºF) isotherm, �� July �� Credit: Budd Christman/UNEP/NOAA �� tion of peat, and are significant sources of �� CH4 as a result of anaerobic decomposi- �� tion (Christensen n.d.). �� While tundra and polar regions play a �� major role in shaping the Earth’s climate, �� they also are highly sensitive ecosystems �� that have the potential to be profoundly � � � Iceland � � affected by changes in the Earth’s climate � � �� (NRDC 2004). Nearly all climate mod- � � � � � �� els indicate that environmental changes � � � �� brought about by global warming are �� U.K. � �� Den. expected to be greater in tundra and polar �� Ger. �� Map of the Arctic Source: Modified from http://www.lib.utexas.edu/maps/islands_oceans_poles/arctic_region_pol02.jpg regions than for most other places on Earth. In that respect, tundra and polar populated regions. Antarctica has no tion balance by changing average surface regions form a sort of early warning system permanent residents. The Arctic has ap- albedo(albedo is the fraction of sunlight for climate change and its effects on the proximately 3.7 million inhabitants from reflected). During the peak of the last planet and its inhabitants. The monitoring eight countries. Sparsely populated and Ice Age, one-third of the Earth’s land of high-latitude and high-altitude eco- relatively undisturbed, tundra and polar surface was covered by thick sheets of ice systems, then, represents a way to detect regions therefore contain the world’s larg- that extended from polar regions toward early signs of regional and global climate est remaining wilderness areas. They also the equator. The high albedo of these ice change. The advance or retreat of possess a surprising range of natural re- sheets reflected a great deal of sunlight glaciers, ice sheets, and sea ice has been sources, from marine life to oil and gas. Yet out into space, which cooled the Earth given particular attention by climate despite their rugged appearance, tundra and allowed the ice sheets to grow. Large change researchers. and polar regions are fragile ecosystems changes in sea ice extent are also thought A rapid warming trend in the Arctic that are extremely sensitive to the effects to influence deep-ocean convection and polar region over the last 25 years has of resource exploitation. Managing these global ocean currents (Jezek 1995). dramatically reduced the region’s sea ice. regions and their resources effectively Many climate and biogeochemical Scientists have been monitoring ongoing places huge demands on both technical studies indicate that carbon cycling in the changes in Arctic sea ice for decades, both and political capacities (SPRI n.d.). Arctic tundra and boreal forests strongly firsthand through fieldwork and remotely Tundra and polar regions also ex- influences global climate as well. Cold tun- through the use of satellite imagery. In ert a profound effect on global climate. dra soils contain huge amounts of stored 2002, the extent of multi-year Arctic sea Variations in the extent of sea ice, for organic carbon. They are known sinks for ice was the lowest on record since satel- example, affect the Earth’s surface radia- atmospheric CO2 through the accumula- lite observations began in 1973. There 261 Case Study: Arctic Seas differs above or below the average for the The extent of Arctic sea ice in September– period 1979-2000. The median ice edge the end of the summer melt period–is the for 1979-2000 is indicated by the black most valuable indicator of the state of the outer line. In 2002, total September ice Quite often, a “low” ice year is followed ice cover. On average, sea ice in September extent was 15 per cent below this average. by recovery the next year. However, Sep- covers an area of about seven million km2, This represents a reduction equivalent to tember of 2003 was also extreme, with 12 an area roughtly equal in size to the conti- an area roughly twice the size of Texas or per cent less ice extent than average. Cacu- nent of Australia. Iraq. From caparisons with records prior to lations performed for 30 September 2004 show a sea ice extent loss of 13.4 per cent, In the images above, the Sea Ice Con- the satellite era, this was probably the least especially pronounced north of Alaska and centration Anomaly scale indicates the amount of sea ice that had covered the eastern Siberia. Source: NSIDC per cent by which the local sea ice extent Arctic over the past 50 years. was only slightly more sea ice present in Researchers also documented tem- America experienced the highest regional 2003. According to one study, perennial perature increases in different regions warming, increasing by 1.06ºC (1.9ºF) per sea ice—sea ice that survives the summer within and near the Arctic Circle, north decade. Greenland cooled by less than and remains year round—is melting at the of 66º. Average temperatures increased one-tenth of a degree C per decade. The alarming rate of 9 per cent per decade by 0.3ºC (0.5ºF) per decade over sea ice cooling found over Greenland was mainly (NASA 2003d). If this trend continues, and by 0.5ºC (0.9ºF) per decade over the at high elevations, while warming trends Arctic sea ice may be gone by the northernmost land areas of Europe and were observed around its periphery. These year 2100. Asia. Temperatures over northern North results are consistent with a National Snow Pancake ice in the Ross Sea, Antarctica Source: Michael Van Woert/UNEP/NOAA 262 and Ice Data Center study that found dinary. Along the Antarctic Peninsula, for record loss of sea ice around Greenland’s instance, the Wordie Ice Shelf has practi- periphery in 2002 (NSIDC n.d.). cally disappeared. In 2002, a section of the As sea ice melts, Arctic waters warm. Larsen B Ice Shelf collapsed—the largest Less ice means more heat gain by polar wa- such event in the last 30 years. ters, which creates a positive feedback lead- In other parts of Antarctica, however, ing to further ice melting and increased ice cover has actually increased (UPI warming. The loss of Arctic sea ice, and 2003). What is happening with the vast the warming of Arctic polar waters, have West Antarctic ice sheet is not yet clear. Between 2000 and 2002, scientists observed the enormous implications for both regional Some studies seem to indicate that it is get- formation of a crack in the Ward Hunt Ice Shelf on the northern shore of Canada’s Ellesmere and global climate patterns. One major ting thicker (NCPPR n.d.). Other studies Island.

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